The present invention relates to an apparatus for performing exercise and a method for using such apparatus and in particular to an apparatus which closely simulates many natural forms of exercise such as cross-country skiing, walking, running, biking, climbing and the like. The present invention further relates to an apparatus for replicating the reciprocating nature of motion during exercise, and more particularly to an apparatus for exercise, rehabilitation, amusement, and/or simulation of human-powered motion. The present invention further relates to an apparatus for strength training and in particular to an apparatus which addresses the natural physiology of the human body.
Many forms of natural exercise (i.e., exercise performed without the use of a stationary exercise machine) provide numerous benefits to an exerciser. In a number of types of natural exercise, a bilateral motion is performed of such a nature that in addition to the work done by a muscle group on one side of the body used, e.g., to attain forward motion in a motive type of exercise, there is simultaneously some amount of resistance to the muscle groups on the other side of the body, typically opposing types of muscle groups, so that both extension and flexion muscle groups are exercised. In a typical bilateral exercise such as cross-country skiing, the exerciser utilizes gluteus maximus and hamstring muscles in the backward stroke and, simultaneously, on the opposite side, quadriceps and hip flexor muscles in the forward stroke. Although various attempts have been made to simulate cross-country ski exercise or other bilateral exercise on a stationary exercise machine, these attempts have not been fully successful in reproducing the experience with sufficient accuracy to provide many of the health benefits of natural exercise. For example, in some ski-type exercise devices, while the trailing limb encounters resistance, the opposite limb encounters virtually no resistance (typically only resistance from fiction of moving machine parts). As a result, many such previous devices include a feature intended to counteract the force of the backward thrusting limb, such as an abdomen pad which receives the forward thrust of the exerciser's body as the exerciser pushes backward against resistance with each leg in an alternating fashion. This abdominal pad keeps the user in a stationary fore/aft position. It is believed that in such (stationary) machines, pushing against the abdominal pad can lead to lower back stress and fatigue and detracts from an accurate simulation of the natural cross-country ski exercise. It is further believed that the lack of forward resistance and the associated lack of balance in such devices lead to a long learning curve such that, to successfully use the machine, a user must develop a new technique for walking or skiing which is very different from that found in nature.
Another feature of many natural bilateral exercises such as skiing, walking, running, jogging, bicycle riding, etc., is that while the exerciser may on average move forward at a constant velocity, the exerciser momentarily accelerates and decelerates as he begins and ends each stroke. As a result, in many natural bilateral exercises, although the exerciser maintains a constant average speed, in fact if one were to travel alongside the exerciser at such constant speed, the exerciser would appear to be oscillating forward and backward with respect to the observer. This constant change in velocity is natural to most forms of human propulsion by virtue of an alternating stride while walking, running, bicycling, etc.
Again, it is believed that many stationary exercise devices fail to reproduce this feature of the natural exercise with sufficient accuracy to provide an enjoyable exercise experience and to provide all the benefits available with natural exercise, such as a more natural and less stressful distribution of force on the joints and development of good balance. For example, with the above-described ski exercise machine, the exerciser is typically pushing against the abdominal pad during substantially most or all of the exercise, thus causing the exerciser to stay in substantially the same position rather than accelerate and decelerate in an oscillating manner as in natural skiing.
A number of forms of natural exercise provide benefits to the upper body as well as the lower body of the exerciser. For example, in cross-country skiing, the exerciser typically pushes using poles. A number of features of the upper body exercise in natural exercise settings are of interest in the context of the present invention. For example, during cross-country skiing, the arm and leg motions are related such that if a skier wishes to maintain constant average speed, exerting greater upper body effort (“poling” with the arms) results in less effort being exerted by the legs, and vice versa. Further, in cross-country skiing, although the arm and leg energy exertions are related, the left and right upper body exertions are independent in the sense that the user does not need to pole in an alternating fashion, much less a fashion which is necessarily synchronized with the leg motions. A cross-country skier may “double pole”, i.e., pushing with both poles at the same time, or may, if desired, push with only a single pole or no poles for a period of time. Another feature of cross-country skiing is that while the skier is moving, when a pole is plunged into the snow, the pole engages a resistance medium which relative to the skier is already in motion, thus providing what may be termed “kinetic resistance”.
Many types of previous exercise devices have failed to provide a completely satisfactory simulation of natural upper body exercise. For example, many previous ski devices provided only for dependent arm motion, i.e., such that the arms were essentially grasping opposite ends of the rope wound around a spindle. In such devices, as the left arm moved backward, the right arm was required to simultaneously move forward substantially the same amount. Thus it was impossible to accurately simulate double poling or poling with a single arm. Many previous devices provided upper body resistance that was entirely unrelated to lower body resistance. In such devices, if an exerciser was expending a given level of effort, by exerting greater upper body efforts, the user was not, thereby, permitted to correspondingly decrease lower body exercises while maintaining the same overall level of effort. Many previous devices having upper body resistance mechanisms provided what may be termed “static resistance” such that when the arm motion began, such as by thrusting or pushing, or pulling backward with one arm, the resistance device was being started up from a stopped position, typically making it necessary to overcome a coefficient of static friction and detracting from the type of kinetic or dynamic resistance experienced in the natural cross-country ski exercise.
Many types of exercise devices establish a speed or otherwise establish a level of user effort in such a fashion that the user must manually make an adjustment or operate a control in order to change the level of effort. Even when an exercise device has a microprocessor or other apparatus for automatically changing levels of effort, these changes are pre-programmed and the user cannot change the level of effort to a level different from the pre-programmed scheme without manually making an adjustment or providing an input to control during the exercise. For example, often a treadmill-style exercise machine is configured to operate at a predetermined level or series of pre-programmed levels, such that when the user wishes to depart from his or her predetermined level or series of levels, the user must make an adjustment or provide other input. In contrast, during natural exercise such as biking, the user may speed up, slow down, change gears, or rest at will.
Additionally, current human motion simulating machines such as exercise bikes, skiers, rowers, etc. have one very important aspect in common; they are considered stationary machines. In other words, the platform on which the user sits or stands is fixed in location. As discussed below, this stationary aspect prevents these devices from realistically exhibiting the sensation of natural motion.
When a person propels a bicycle, cross country skis, row boat, etc., there are subtle fore and aft motions encountered by both the person and the vehicle. Although the amplitude and duration of these motions are somewhat specific to a particular vehicle, they are all tied directly to the force output generated by the person propelling the vehicle. For example, when a person rides a bicycle, these subtle motions occur as a result of his pedaling, and the reciprocating action of the user's legs is what ultimately motivates the bicycle in a forward direction. When closely examining the physics behind the forward motion of a bicycle it becomes apparent that the bicycle and user are in a continual state of acceleration and deceleration while the user pedals. This is due to the fact that when the user exerts a force on one of the pedals, the bicycle and user accelerate until that pedal begins to approach the bottom of its stroke, at which point the bicycle and user begin to decelerate. As the opposite pedal reaches the top of its stroke, this cycle begins again. As a result, the cyclist is in a constant state of acceleration and deceleration. This oscillating motion can be easily witnessed by driving in a car at a constant speed along side a cyclist. From the perspective of an occupant of the car looking out a side window, the rider will appear to move fore and aft in a manner directly related to his pedaling cadence. This fore and aft movement will generally be between a range of one-half of an inch on level or downhill terrain to several inches on an uphill grade.
When a rider encounters a hill, he generally changes the gear ratio of his bike by “changing gears” such that a lower ratio is used. The rider can therefore maintain the same cadence and force output as he would on level ground resulting in a slower speed up hill. For example, it is the goal of a profession cyclist to maintain a relatively steady cadence, normally 80-100 strokes per minute. This is the case whether riding on level terrain, uphill or downhill. The use of a gearing system ensures that a constant cadence is maintained, even though the speed of the bicycle may vary drastically.
The use of a gearing system also affects the motion of the vehicle being ridden. For example, the fore and aft oscillation of a bicycle is much greater in low gear vs. high gear due to the increased torque applied to the drive wheel. As a result, in low gear there is much less stress on the leg joints and muscles. This is particularly important in physical therapy and rehabilitation. For example, a person recovering from reconstructive knee surgery may be advised by a physician to exercise the knee with very low exertion. In this case, it would be advantageous for the person to exercise on a bicycle in a low gear ratio to reduce stress on the recovering knee.
An important aspect of natural human motion is the concept of rest. For example, during the deceleration phase of the oscillation described above, the muscles experience a short period of rest. This rest period increases as the period of oscillation increases. When a rider pushes a pedal once every few seconds, the bicycle coasts during the rest periods.
Current exercise bicycles generally include a user seat on a frame with a set of pedals which spin a flywheel. The flywheel is magnetically or otherwise braked to give resistance to the user's legs. These machines generally simulate hill climbing by simply adding greater resistance to the flywheel which requires either a greater force output or slower pedaling cadence by the user and adds increased pressure to the legs and joints. The stationary nature of these machines precludes the user from experiencing the fore and aft motion encountered while using a real bicycle. Instead, although the user's body strains to oscillate forward and backward, the stationary aspect of the machine keeps him fixed in one place. This causes a jerky sensation which translates into an uncomfortable and non-motivating activity, as well as the potentially dangerous wear and tear on the user's joints and muscles.
The solid line in the chart of FIG. 13 depicts the force exerted by a user's foot on the pedal of an actual bicycle during a pedal stroke. From this chart, it becomes apparent that the forward acceleration of the bicycle and rider reduces the initial force exerted against the pedal when the knee is bent the most. This greatly reduces the stress to knee and leg muscles when compared to a stationary bike which requires the user's full force from the very beginning of the stroke. See the dashed line of FIG. 13.
Similar principles apply to the activity of natural rowing when compared to the use of a stationary rowing exercise machine. When rowing a boat with a sliding seat, the user straps his feet to a stationary part of the boat and sits on a seat facing rearward which can slide fore and aft. At the beginning of the stroke, the user bends his knees so as to bring his body toward the rear of the boat. He then extends his arms fully and engages the oar blades into the water. Next he straightens his legs and pulls the oars toward his torso. At the end of each stroke, the user pulls the oar blades out of the water and returns to the beginning of his stroke to start the sequence again.
As with the bicycle, a person following alongside a rower at a steady speed will observe the boat and user oscillating fore and aft with each stroke. As the user engages the oar blades and begins his stroke (the power stroke), the boat and user accelerate forward. When the user reaches the end of his stroke and returns (return stroke) to the starting position, the boat and user decelerate. Relative to the observer, this oscillation will be considerably greater than that of a bicycle, and, depending on the amount of time the user takes on his return stroke, may exceed one foot.
Most rowing exercise machines confine a user to a fixed location, i.e. the user's feet are strapped to a stationary pad. These designs don't allow for any fore and aft movement of the user's body other than the sliding of the seat. This results in a jerking sensation at the beginning and end of each stroke. These rowing machines can cause strain on the back and legs and over-compression of the knees. See FIG. 13.
These stationary exercise bike and rower examples demonstrate the need for a more realistic exercise machine capable of accurately replicating the forces of nature as they apply to human powered locomotion devices. The present invention overcomes the above-mentioned obstacles and can be applied to any type of exercise device which uses the reciprocating nature of human motion such as a bike machine, a rowing machine, a cross-country ski machine and any other reciprocating motion apparatus and the like. The present invention can be likened to a human propelled differential motion machine, much like the differential on an automobile. In particular, a dynamic element moves in one direction (input 1), the user mounts a carriage and motivates a drive wheel (or the like) in the opposite direction (input 2), and the user and carriage move based on the difference between the two inputs, or the differential.
Along with providing a more realistic machine for accurately replicating the forces of nature as they apply to cardiovascular exercise devices, the present invention also provides a similarly realistic machine for accurately maximizing strength exercise. Coupled with cardiovascular training, strength training is an important part of maintaining optimal physical fitness.
Strength training involves applying a force against a resistance over a range of motion. Human anatomy limits the amount of force a user can produce at any one position throughout this range, and the magnitude of force which can be safely applied at any point can vary considerably.
For example, when exercising the triceps muscles, a person begins with forearms flexed at the elbows (e.g. 45 degrees) and pushes against a resistance until the elbows are fully extended (e.g. 180 degrees). The lever arm at the elbow where the triceps attaches to the forearm is shorter during flexion than during extension. As a result, a person's force output capability increases as the forearm is extended. See FIG. 23. A functional triceps exercise would therefore apply a variable force, starting low at the beginning of the stroke and increasing throughout extension.
As such, some forms of strength training can feel unnatural and even cause injury. An injury can further complicate the optimal force which an individual can apply during the range of motion. For example a person with tendonitis of the elbow may feel the greatest discomfort halfway through the range of motion (e.g. 112.5 degrees). The optimal force output for this person might be 5 lbs at 45 degrees, 10 lbs at 72 degrees, 3 lbs at 99 degrees, 10 lbs at 126 degrees, 20 lbs at 153 degrees and 18 lbs at 180 degrees. See FIG. 24.
Lifting weights is one of the most popular forms of strength training This can involve lifting free weights, using linkages or cables attached to weights. Weight lifting involves lifting and lowering a fixed weight. The profile of the force application to the user is counterintuitive. For example, a weight bearing cable pull-down exercise performed for exercising the triceps generally involves running a cable over a pulley at head level and down to a fixed weight. The user grasps a handle on the other end of the cable, suspends the weight with elbows fully flexed, and then begins the motion of extending the upper arms downward until full extension is achieved. He then returns to the flexed position and repeats the move.
Assuming the use of a 25 lb. weight, the force applied to the user prior to beginning the move is 25 lbs. At this point the weight is hanging, but not moving. As soon as the user begins the motion, he has to accelerate the weight from a stopped position causing a brief impulse force (F=ma). This impulse force will generally range from 25% to 50% of the weight being used and its effect is added to the weight itself. Once the weight is up to speed, the force drops to 25 lbs., and as the user reaches the end of the stroke and decelerates the weight, there is a negative impulse force (force reduction). As a result, the user experiences a force of as much as 37.5 lbs. at his weakest position, and as little as 12.5 lbs. at his strongest position. See FIG. 25.
Spring resistance is another form of strength training. Using linkages or cables attached to springs, these machines allow users to exercise a variety of muscle groups. Spring loaded strength exercisers generally rely on winding a spring throughout the range of motion. In this case, the force application generally begins at some predetermined amount and then increases throughout the range of motion based on the spring constant. See FIG. 26.
Flywheel/resistance based machines, utilizing linkages or cables to allow the user to exercise, are yet another form of strength training. These machines can offer a complex variety of forces depending on speed and frequency repetition. These machines generally utilize a speed dependant resistance mechanism such that the faster the user pulls, the greater the resistance. The force application also includes a “tare” component necessary to power the device and keep the flywheel rotating. See FIG. 27.
Most strength training machines/techniques require a user to choose a weight or resistance based on the weakest point throughout his range of motion. This limits the effectiveness of the workout by not taxing the muscles enough during the stronger points throughout the range of motion.
Additionally it becomes “hit or miss” when trying to determine the maximum force a user can apply. For example, determining the maximum weight that can be bench pressed requires the user to try consecutively larger amounts until the weight cannot be lifted. Going through this process weakens the user with each consecutive try which makes the results unreliable.
The above mentioned forms of strength exercise cannot address the natural physiology of the human body. Additionally, the complex profile of the ideal force applied over the range of motion (functional strength training) not only varies from one exercise to another or one person to another, but from one repetition to another.
Accordingly, it would therefore be advantageous to utilize a strength exercise which allows the user to apply a varying force of his choosing throughout the range of motion.
It is a general objective of the present invention to provide a speed controlled strength machine such that resistance (torque) is user dependent.
It is another general object of the present invention to provide a strength exercise machine which allows a user to exercise in a functional manner with improved safety and effectiveness.
It is another object of the present invention to provide a strength exercise machine which allows a user to easily determine their maximum force output at any given time.
It is a more specific object of the present invention to provide a strength exercise machine which allows a user to vary the force output at any time throughout the range of motion.
Yet another object of the present invention is to provide a strength exercise machine which allows a user to alternate from one strength exercise to another without making any adjustments to the machine.
Yet another object of the present invention is to provide a strength exercise machine which allows the user to apply a different amount of force from limb to limb.
Yet another object of the present invention is to provide a strength exercise machine which allows the user to exercise at various speeds.
Another object of the present invention is to provide a strength training exercise machine which displays the amount of force being produced by the user at any point throughout the range of motion.
Another object of the present invention is to provide a strength exercise machine which displays a workout regimen to coach the user from one strength exercise to the next.
Yet another object of the present invention is to provide a strength exercise machine which allows opposing muscle groups to be exercised simultaneously.
Another object of the present invention is to provide a strength exercise machine which displays speed of motion, number of repetitions and range of motion.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.